How does the Aruba AP confirm whether it has the same image as the controller and when does it fallback to TFTP boot?
Product and Software: This article applies to all Aruba APs without a provisioning image and ArubaOS. RAP-2WG, RAP-5WN, and RAP5 have a built-in provisioning image and their behavior is not the same as described in this article.
An AP boots up based on the BootCMD environment variable. The two boot modes available in the BootCMD environment variable for an AP are:
- Boot AP
The Boot AP is the default mode. The apboot performs a checksum on the image, which is available in its flash. If the checksum is good, the AP loads the image to the memory. If the checksum is bad, the AP falls back to TFTPboot.
TFTPboot starts the apboot process to get an IP address. If the AP is set for DHCP, the AP gets the IP address of the TFTP server configured in the option 43, and the image is transferred from the TFTP server (controller). If the apboot has static parameters, the AP will use the environment variable "serverip" for downloading the image.
After the image is loaded into the memory, the AP will compare the running image version with the version on the controller. If the images are the same, the AP starts functioning. If the images are not the same, the AP upgrades it's image to be the same as that on the controller. After the AP upgrades its image, it reboots and comes up on the controller following the regular ap boot procedure.